Tuning biomechanical behavior and biocompatibility of Mg–Zn–Ca alloys by Mn₃O₄ incorporated plasma electrolytic oxidation coatings

In this study, the mechanical behavior and biocompatibility of plasma electrolytic oxidation (PEO)-coated Mg–Zn–Ca alloy specimens were investigated. The coatings were synthesized by incorporating KMnO₄ and Mn₃O₄ nanoparticles into an electrolytic solution. An indentation test revealed a significant increase in the reduced elastic modulus of the PEO coatings with incorporated Mn₃O₄ under various loads. This increase was attributed to the higher coating thickness and reduced porosity achieved by the addition of Mn-based additives to the electrolyte. The composite PEO coatings prepared with Mn₃O₄ nanoparticles exhibited a more pronounced reduction in elastic modulus under pressure. Wettability tests showed that the prepared coatings maintained their hydrophilic nature with water contact angles in the range of 25–63°. The presence of Mn₃O₄ in the PEO coatings provided a conducive environment for cell viability. The enhanced biocompatibility of the composite coatings achieved by incorporating KMnO₄ into the electrolyte was particularly noteworthy. This improvement was attributed to the controlled release of Mn ions, which generates a microenvironment that favors cellular activities. The study showed that incorporating Mn₃O₄ into PEO coatings enhances mechanical properties, preserves hydrophilicity, and improves biocompatibility, thus indicating its potential for orthopedic implant applications.